GLC determination of lasalocid and its bromo analog as their silyl derivatives

A GLC method is presented for the determination of lasalocid and its bromo analog. The method is based on the quantitative trimethylsilylation of the compounds without any molecular cleavage, followed by chromatography on a nonpolar silicone column. Silylation was carried out directly without any extraction or prior cleanup, despite the complexity of the dosage forms. This procedure was used for the assay of pure substances, pellets, premixes, experimental ampul solutions, and mycelial filter cakes. The results were in good agreement with data obtained by microbiological procedures.